In R, how do I transform a complex list object into a dataframe object-CodePudding

I have a dataset retrieved from an.RData file. If use head() my data looks like this:

>head(df,1)

      R123    R456   
cg1   1.252   1.282

Using the "typeof()" command tells me the data type is a list. However, if I use "class()" my output is data.frame:

>typeof(df)

>class(df)
"data.frame"

Furthermore, I can use commands like df$ and my output looks like this

>df$R123
1.252   1.895

which returns the values corresponding to cg1 and cg2 rows. Using df[1,] and df[,1] gives me an output like this:

>df[1,]
     R123    R456
cg1  1.252   1.252              

>df[,2]
1.252   1.895

I used rownames() to confirm that cgX are row names These are my questions:

Can someone explain this type of data format this is?
Can someone explain how I would transform this data into the "Long" format data frame?

I would like to get the dataset in the "long" format so that it may be easier to analyze. The ideal format would look like this:

Individual_ID     cg_site    value
R123              cg1        1.252
R123              cg2        1.895   
R456              cg1        1.282
R456              cg2        1.572

If context helps. The data is about DNA methylation sites. The RXYZ is an ID number, the cgX is a location, and the numerical values are quantities of methylation activities. The real dataset is quite massive, making doing this transformation manually very difficult a difficult task.

CodePudding user response：

It is just a data.frame with rownames as well. If we want to create three columns, one with column name, second with row name and the third with value, an easier option is to create table object and coerce it to data.frame with as.data.frame

as.data.frame.table(as.matrix(df))